220 



SCIENTIFIC AGRICULTURE 



March, 1922. 



Included in the forty strains of staphylo- 

 cocci are ten strains which liave been re- 

 covered from air — see page 216. Refer- 

 ence to pp. 217-218 shows that the staphy- 

 lococci from air are of the same main type 

 as those isolated from milk, but that their 

 ability to dissolve milk is much less mark- 

 ed. The number of our strains is quite in- 

 sufficient to warrant the drawing of con- 

 clusions. Yet, our results liave some slight 

 significance with respect to tlie relation- 

 ship of the air contamination of milk dur- 

 ing the milking operations. "We do not dis- 

 .sent from the conclusions of Harding et 

 al, (30) Ruehle and Kulp, (31) Ayers et 

 al, (34), and others relating to the minor 

 part played in the contamination of milk 

 l)y organisms from the air. We record our 

 findings but do not propose to comment 

 thereon. It is permissible to cite the re- 

 covery by Gordon -(33) of two strains of 

 gelatin-liquefying-milk-clotting-cocci from 

 the open air of London; and the work of 

 the Winslows (84) in which they found 

 aurocoeci from the air. 



Apart from the staphylococci, we do not 

 consider that the remaining types included 

 in our studies, place themselves in suffi- 

 ciently large groups t-o warrant any de- 

 tailed comment. It should be noted that 

 the cultures from feeds and bedding are 

 principally in Group I — milk dissolved 

 laterally ^- and are Gram positive or Gram 

 negative rods; some ferment glucose and 

 lactose to acid and gas and some, but not 

 all, liquefy gelatin. The agreement with 

 the work of previous researches in the iso- 

 lation from feeds of lactase-fernienting 

 strains is to be noted. (40) (41). Of the 

 cultures recovered from water, the major- 

 ity are placed in our Group III — milk di- 

 gested with putrid odour. The reactions 

 of these cultures, as shown in Ta])le II pre- 

 sent much variation; and tlie number of 

 strains is small. Even so, the relation of 

 the source of the organisms to the definite 

 production by them of putridity in milk 

 .should not be overlooked. 



Detailed Cultural Studies. 

 In pursuit of more definite information 

 with regard to the characteristics of the 

 organisms included in our studies, four of 

 tlie strains which produced tlie "lateral'' 

 type of "milk dis.solving", and two of the 

 milk putrefying .strains have been ex- 

 amined in greater detail. 



Culhire 63. — The characteristics of this 

 culture, are, with very minor exceptions 

 common to those of the four cultures, 63, 

 75, 86 and 122, which, by rea.son of the 

 fact that they produce the "lateral" type 

 of dissolving, have been .submitted to a 

 detailed study. The cultures were isolated 

 from middle milk of Cow 98, middle milk 

 of Cow 121, strippings of Cow 51, and 

 strippings of Cow 86, respectively. 



MorpJiology. — Microscopically cocci oc- 

 curring singly and in irregular groups, 

 varying in diameter from .4 u. to 1.4 u. 

 the majority about 1 u ; non motile ; stain- 

 ing well with Kuhne's methylene blue: 

 Gram positive. 



Cultural Characteristics : 

 Agar Stroke at 37^/2 deg. C. In 24 hours 

 growth moderate along track of needle, 

 beaded, glistening, vellowish bv transmitted 

 light. 



Gelatin Stab at Room Temp. — In two 

 days no apparent growth ; in 6 days bead- 

 ed growth along line of puncture, growth 

 best at bottom of stab, yellow; in 18 days 

 liquefaction begun, " inf undibulif orm ; in 

 one month liquefaction complete. 



Nutrient Broth at 371/0 deg. C. — In 24 

 hours iridescent ring at surface. Strong 

 clouding, caramel odor, sediment scanty, 

 viscid on agitation ; in 3 days no odour. 



Agar Colonies at 371/2 deg. C. — In 48 

 hours growth moderate, surface colonies 

 .75 to 1 mm. in diameter, circular, smooth, 

 flat, yellowish ; amorphous structure. Deep 

 colonies, torpedo shaped, varying in lengtli 

 to .75 mm., distinctly yellow. Under low 

 power objective, compact and veiy finely 

 granular. 



Gelatin Colonies at Boom Temperature. 

 (1st appearance) in ten days minute col- 

 onies; in 20 days circular surface colonies 

 varying in diameter, to 1 mm., .smooth, 

 flat, yellow; amorphous structure; lique- 

 faction, cup shaped, 2 mm. in diameter; 

 subsurface colonies, small about .25 mm. 

 elliptical, yellow. 



Physiology : 



Milk at 371/4 deg. V. — In 24 hours, clot- 

 ted, beginning to dissolve "laterally" 

 faint caramel odor; in 48 hours one-third 

 dis.solved; in 72 hours one-half dissolved, 

 fluid later becoming clear and colourless; 

 in 21 days three-quarters dissolved, the 

 .solution yellow; in one month no further 

 dissolving and no odor to be noted ; white 



